Traditionally, jammers are currently to be found in the form of vehicle-mounted electronic units with associated directional antennas that are directed towards the area that is to be exposed to jamming signals. The jammers utilize high outputs in order to achieve a long range. The position of such conventional jammers is easy to determine by taking bearings and the position of the jammer can be regarded as having been disclosed when the jamming commences. In addition, the traditional jammers that are located at a great distance from the target objects that are to be jammed have a low efficiency, as the electromagnetic radiation from these jammers decreases with distance and hence the electromagnetic radiation that is transmitted with a high output must travel a long way before the radiation acts as interference on the target object. In addition, these conventional jammers are difficult to construct and expensive to maintain on account of the high output that has to be able to be handled. Conventional jammers are vulnerable in the sense that the whole ability to jam can be disabled by a single strike.
It can also be the case that jammers are fired out or placed in some other way into an area that is to be jammed. The distributed transmitters disclose their position when transmitting commences and if several jammers are arranged within a limited area, there is normally no provision for coordinating the jamming functions.
However, jamming arrangements have recently been proposed with several coordinated jammers, see U.S. Pat. No. 6,414,622 B1. According to the said US patent, a plurality of jammers is in contact with and under the control of a sensor via data links. Such an arrangement is less vulnerable than the conventional jammers, as the arrangement can be regarded as being able to maintain a certain degree of functionality even if one jammer is disabled. A weakness in the arrangement is, however, the dependency on the sensor and hence the lack of autonomy for the jammers. If the sensor or its data link to the jammers is disabled, the whole installation will be disabled.